I brought a Cold/Ice and a Storm/Ice both to 50, fully IO'd, def caps, incarnate slots, permahasten, etc. In the long run, they both end up being completely different playstyles. If your plan is just to hit 50, then a lot of teaming will be centered around freezing rain/sleet for both since neither really come into their own until you start getting your invention sets. Cold is a lot more versatile with its buffs, and also has probably the best single target debuff in the game (Benumb) so its great against AVs. Heat Loss will give your team unlimited endurance, which was amazing back in the day because it was one of the only sources of End Rcv that could out recover the -recovery effects of Tier 9 blast powers. but with the new leadership power and no more -End Rcv on blast powers it makes heat loss almost irrelevant (still provides a hefty -res debuff though). My Cold/Ice was my preferred hero whenever it came to teams, tfs, AVs etc, and also my main.
Storm on the other hand was just downright CHAOS! It was the most fun character I ever soloed with. With Hover and good positioning, your foes will always suffer heavy -acc debuffs and never get near you with hurricane (you also feel like a sheep herding dog). The best part though was having 3 Tornadoes and 3 lightning storms out at all times. Lightning storm is one of the coolest graphics/audio effects in the game, so if you want chaos, flashy, and pure fun then storm summoning is for you!
Ice has always been my favorite ranged power set, but they were particularly good on defenders because 2 of the powers (Ice storm and Blizzard) scaled to blaster damage. They were actually considered summoned "pets" with their own damage scaling, affected by your own damage buffs during the instance they were summoned. And with Cold/Ice I could have Aim/sleet/blizzard/ice storm/heatloss up every ~30 seconds or so and take out +3 mobs with ease. This coupled with amazing single target holds and synergystic themes made ice such an easy pick as my secondaries for both.